Blackboard



(N Q WEISSENBORN.

V 'BLAGKBOARD5Q I No..483,371 Patented Sept. 27, 1892.

WITNESSES:

UNITED STATES PATENT OFFICE.

osoAR A. WEISSENBORN, or JERSEY CITY, NEW JERSEY.

BLACKBOARD.

SPECIFICATION forming part of Letters Patent No. 483,371, datedSeptember 27,1892.

Application filed October 12, 1391. Serial No. 408,415. (No model.)

To all whom it may concern:

Be it known that I, OSCAR A. WEIssENBoEN, a citizen of the UnitedStates, residing at JerseyGity, Hudson county, and State of New Jersey,have invented certain new and useful Improvements in Blackboards, ofwhich the following is a specification.

My invention relates especially to that class of blackboards in whichthe board proper is composed of a sheet or apron of what is known asslated cloth; and my invention consists of a certain novel arrangementof apron-supporting rollers and concomitant parts, as hereinafter fullydescribed, whereby different parts of the apron may be successivelyexposed for use in either direction of its length, the exposed part iskept always in a state of tension, and the rollers are capable ofoperation independently of each other with ease and facility.

In the accompanying drawings, Figure 1 represents a face view of ablackboard embodying my invention. Fig. II represents a Verticalcrosssection thereof. Fig. III represents a side view thereof. Fig. IVrepresents a horizontal section thereof.

Similar letters of reference indicate similar parts.

The letter A indicates the slated-cloth apron, and B 13 two rollerslying in horizontal planes, one above the other, to each of whichrollers one end of said apron is connected in such a manner that theapron may be alternately wound and unwound on and ofi from either of therollers. A part of the apron A is thus exposed between the rollers B B,as shown, forming a writing-surface, the area of which is determined bythe distance between the rollers, and in order to properly sustain thisexposed part of the apron in usea backing 0, of suitable area andmaterial, is mounted opposite thereto on the blackboard-frame, thisbacking, together with bars or uprights D D, one at each side and one atthe center, constituting the frame. To each of the vertical edges of thebacking C is fastened a cleat e, which acts as a guide for either edgeof the apron by receiving such edge, as shown. The side bars D D of theframe carry the bearings for the shafts of the rollers B B, and on theshaft of the upper roller is mounted a pulley F, while on the shaft ofthe lower roller is mounted a crank or winch G, both the pulley andcrank being at one and the same side of the frame. At a point adjacentto the lower roller is an auxiliary pulley I,which lies in the verticalplane of the roller-pulley F and which is joined thereto by a suitableband J. The shaft of the auxiliary pulley I has its bearing on theproper side bar D, and on this pulley-shaft is also mounted a crank G.By this arrangement the operation of the lower roller may be effected bythe crank G and that of the upper roller by the crank G, together withthe pulleys F I and band J, and due to the juxtaposition of said twocranks the greatest ease and facility is afforded to the operator inadjusting the apron.

by the rollers irrespective of the distance between the rollers.

In blackboards of small construction the auxiliary pulley I, &c., may bedone away with, the operator in that event working the top roller bymeans of a crank on its shaft.

By winding the apron A on the two rollers B B the exposed part of theapron opposite the backing O is kept always in a taut or stretchedcondition, which is requisite to the successful use of the apron as ablackboard, and by said winding of the apron, moreover, every portion ofwhich is not in actual use is protected against dust and atmosphericinfluences. The operation of the rollers 13 B is controlled by means ofpawls Z, engaging with ratchet-wheels Z, which are mounted on the shaftsof the lower roller and pulley I, and the tension of the apron A may beregulated by means of set-screws, which are fitted in theseveralbearings of the structure to act on the shafts.

At the lower edge of the backing O is a ledge or shelf S, which extendsentirely across the blackboard-frame, it being properly mounted on thecleats e, as shown, or other suitable part. The chief purpose of thisshelf S is to form a receptacle for pieces of chalk and otherobjectionable matter, preventing access thereof to the folds of theapron as it winds on the lower roller.

In order to obviate an undesirable warping of the backing 0 when it isof wood, it may be curved from top to bottom outward, or in thedirection of the apron rendering it convex, as shown in Fig. II, thisshape also more readily to lie against the backing, and, if desired, thebacking may be covered with cloth or like material, as at 0, so as topresent a soft or yielding surface.

What I claim as my invention, and desire to secure by Letters Patent, is

A blackboard having, in combination, the Winding-apron of slated cloth,the apron-supporting rollers, a means for operating the rollersindependently of each other, and the frame having a backing with aconvex surface presented to the apron, and cleats forming guides for theedges of the apron, substantially as shown and described.

OSCAR A. WEISSENBORN. In presence of Lotus W. FROST, R. T. VAN BOSKER.

